The present invention relates to a novel part structure for metal ornamentation which enables attachment of ornamentation to finished appliance and auto bodies by welding, and more particularly, to one which permits welding through paint and through vinyl coverings without discoloring areas adjacent the welds, and which seals the welds against corrosion.
In the appliance and automobile industries, ornamentation such as nameplates, medallions, letters, and script has generally been attached to finished body panels by means of various fasteners which require mounting holes. Studs, integral with the ornament, are pushed through the mounting holes, and must then be fastened with thread-cutting stampings filled with a sealer, using a power tool. A particular pattern of mounting holes is required for each type of ornamentation. In the automobile industry especially, many models are produced from the same basic body, and each is identified by a different ornamentation. Since there is no common hole pattern, the basic body cannot be prepunched to accommodate the several types of ornamentation needed for the model types produced. As a result, automakers are forced to drill from 50 to 70 percent of these holes by hand, on the assembly line. Only those certain holes which are common to all models can be prepunched.
Although the hole drilling on the production line is fixtured, pressure on the drill flexes the unsupported panel inwardly, elongating the hole, and changing its spacing with respect to adjacent holes. Many types of ornaments, especially the push-in type applied to the front side of a panel, require close fitting holes for adequate retention and sealing of the cut metal surfaces. Where the holes have been elongated and torn, corrosion can occur. Where spacing is improper, ornament breakage is common during assembly, as well as loose ornaments which fail to hold, and stick out from the side of the body. Rust streaks appear even on new cars, where the hand drilled holes have not been completely sealed.
Prepunched hole costs and hand drilled hole costs, multiplied by the 20 or 25 per body for ornamentation mounting, add up to millions of dollars annually in direct labor. In addition, ornament placement is limited to locations where there is no structure behind the panel, and often to where access is available from the inside, in order to make a proper attachment. This frequently results in less than the best aesthetics, and much of the effectiveness of the ornament may be lost. Efforts to overcome this difficulty by use of fasteners that can be driven in from the front now are used in about 10 percent of all ornament attachments. However, these are very easily removed by vandals, and are also subject to being detached in car washes, especially if the body holes have any amount of elongation.
In 90 percent of the ornament attachments, thread cutting devices are power driven onto the ornament studs from the back side of the panel. The power tool is often used at extreme angles due to access conditions, and studs are frequently cut off during the operation, requiring repairs. Often the job requires two men, one to hold the ornament or letters in position on the front side of the panel, and a second man to apply the fasteners on the opposite side.
When attaching through vinyl covered panels, the vinyl often has prepunched holes to match body holes, and it requires specially trained, premium paid workers to lay and apply the vinyl covering so that the holes match and the ornaments can be attached.
Efforts are constantly being made to eliminate the high costs and problems resulting from the use of fasteners which require mounting holes in the body, by attaching ornaments and trim with adhesives. However, the fine oil mist prevalent in assembly plants, as well as the fine dust, the spatters of grease, fingerprints, etc. on the finished bodies tend to defeat adhesive attachments. One sees letters missing from automobiles, and the longer trim strips are often seen at the sides of highways. On paints with some metallic pigments, long a favorite in the industry, adhesives are much reduced in holding ability. At best, they can only grip the paint, not the body, and paint adhesion to the body is a constant industry problem. If such an attachment pulls away, it could remove an area of body paint leaving an unsightly condition.
Delicate script ornaments have very little attachment area for an adhesive, and attachments must depend on area for strength. Therefore, they do not adhere to the body reliably.
Larger pieces of die cast metal script have another problem. The curves in body panels are not all identical from body to body, and there is also some warp often found in the script or nameplate. Adhesive mounting of such pieces is not strong enough to straighten out the warp, or to force a script piece to follow a wandering panel curve, and failures result.
Various methods of ornament attachment by welding have been proposed, but no system is currently able to meet all of the requirements for the attachment of metal ornamentation.